Safing and arming devices are generally provided in munitions as part of a fuze assembly to ensure that the munition is not armed and detonated until certain conditions have been met. For projected munitions, an environmental sensing device (ESD) can be provided to sense some phenomenon of the trajectory (e.g. an acceleration level or acceleration-time interval) of the projected munition prior to furnishing a switch closure or signal for arming the device prior to reaching an endpoint of the trajectory. Conventional safing and arming devices (see e.g. U.S. Pat. No. 5,693,906) are formed from a plurality of machined metal parts using hand assembly. The machining of many individual parts which must be made with close tolerances and then assembled by hand is relatively expensive and also results in a completed device which is relatively bulky. More recently, microelectromechanical systems (MEMS) and LIGA (an acronym for “Lithographic Galvanoforming Abforming” which is a process for fabricating millimeter-sized mechanical or electromechanical devices based on building up the structure of the LIGA devices by photolithographic definition using an x-ray or synchrotron source and metal plating or deposition) technology have been combined to fabricate relatively complicated safing and arming devices utilizing a zig-zag delay and which require a separate moveable slider for each acceleration being sensed (see e.g. U.S. Pat. Nos. 6,167,809; 6,314,887; and 6,568,329).
The present invention represents an advance over the prior art by providing a two-stage acceleration sensing apparatus that is considerably simpler in construction than prior art devices and which can be readily adapted to provide different types of safing and arming capabilities based on electrical, optical or explosive functionality, or a combination thereof.
The present invention also provides a uniform design architecture which can be readily adapted during design and manufacture to form safing and arming devices which are enabled by predetermined acceleration components which can range from less than a few Gs up to tens or hundreds of thousands of Gs depending upon a particular application of the apparatus.
The present invention further provides a safing and arming device which can be formed using conventional semiconductor integrated circuit (IC) technology, with a large number of devices being formed on a common wafer and then separated as a final step in manufacture. This can reduce manufacturing cost and eliminate the need for piece part assembly.
These and other advantages of the present invention will become evident to those skilled in the art.